A former boss at the hospital where Lucy Letby worked has been arrested on suspicion of perverting the course of justice.

Police arrested the suspect on Wednesday as part of an investigation into allegations of gross negligence manslaughter by former senior leaders at the Countess of Chester hospital.

Unusually, Cheshire constabulary declined to confirm the age or gender of the person arrested. However, the force confirmed that they were one of the three former hospital bosses arrested last June on suspicion of gross negligence manslaughter.

Letby, 36, is serving a whole-life prison sentence after being convicted of murdering seven babies and attempting to kill seven others in the year to June 2016. The former neonatal nurse denies the allegations and is seeking to challenge the convictions through the Criminal Cases Review Commission (CCRC), which can refer potential miscarriages of justice to the court of appeal to be reviewed.

Cheshire constabulary said: “On Wednesday 22 April, officers from Cheshire constabulary executed a search warrant at a property in connection with Operation Duet. Operation Duet is the ongoing investigation into corporate manslaughter and gross negligence manslaughter at the Countess of Chester hospital.

“An individual was arrested on suspicion of perverting the course of justice. They have subsequently been bailed pending further inquiries. The searches at the property have now concluded.

“Both the corporate manslaughter and gross negligence manslaughter elements of the investigation are continuing and there are no set timescales for these.”

Cheshire constabulary launched an investigation into corporate manslaughter at the Countess of Chester in October 2023 after Letby’s first trial. The investigation, Operation Duet, focuses on senior leadership and decision-making to determine whether any criminality has taken place in relation to their response to the increased baby deaths on the neonatal unit.

In March 2025, the criminal inquiry was widened to include gross negligence manslaughter, which centres on the actions of individuals. A public inquiry that examined the role of hospital bosses was due to publish its findings in early 2026, having finished hearing evidence in March 2025.

Earlier this week, the inquiry, chaired by Lady Justice Thirlwall, said work on the report was ongoing and that it was unable to confirm a date for its release. The arrests of the three former hospital bosses mean contempt of court restrictions apply to any material that could prejudice a jury that may consider the charges in a criminal trial.

Letby has twice unsuccessfully attempted to overturn her convictions at the court of appeal in London. The CCRC has been examining evidence said to cast doubt on her guilt since February last year.

Prosecutors announced in January that Letby would not face further charges after considering a file of evidence from Cheshire constabulary.

The Crown Prosecution Service had considered 11 new offences: two of murder and two of attempted murder in relation to two babies who died, and seven of attempted murder in relation to seven babies who survived.

The new allegations included the alleged murder of a baby at the Countess of Chester hospital and another at Liverpool Women’s hospital. However, the CPS said the evidence did not meet the test required to bring fresh charges.